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东营凹陷已发现的中深层裂解气主要分布在利津—民丰地区的古近系沙河街组第四段储层中,其来源为洼陷区沙四下亚段烃源岩。以沙四下亚段烃源岩的生烃史恢复为基础,结合成岩矿物流体包裹体和天然气成藏地质背景,对该区中深层裂解气藏的形成时间和充注期次进行了分析。结果表明,利津—民丰地区沙四下亚段烃源岩具有两期生烃过程,第一期以生油为主,第二期生成大量油气;沙四下亚段自下而上3套烃源岩达到生成裂解气的时期分别为东营组沉积初期、东营组沉积末期和馆陶组沉积末期;沙四下亚段储层具有两期油气充注过程:第一期为沙二段—东营组沉积末期,以充注原油为主;第二期从馆陶组沉积末期开始,一直持续至今,该期又可分为两个阶段:馆陶—明化镇组沉积初期以充注原油为主,明化镇组沉积中期至今以充注裂解气为主;构造高部位地区仅存在第二期原油的充注。
The middle-deep cleavage gas discovered in Dongying sag is mainly distributed in the fourth member of the Paleogene Shahejie Formation in the Lijin-Minfeng area, and its source is the source rocks of the Lower Es4 in the depression area. Based on the restoration of hydrocarbon generation history of the source rocks of the sub-fourth member of the Shahejie Formation, combining with the fluid inclusions of diagenetic minerals and the geological background of gas accumulation, the formation time and filling period of the intermediate and deep pyrolysis gas reservoirs were analyzed. The results show that there are two hydrocarbon generation processes in the source rocks of the Lower Es4 in Lijin-Minfeng area. The first period is mainly oil generation and the second generation is large amount of oil and gas. Three sets of bottom-up three sets of hydrocarbons The source rocks reached the stage of pyrolysis gas generation during the deposition of Dongying Formation, the sedimentation of Dongying Formation and the sedimentary end of Guantao Formation respectively. The reservoir of Shahejie Formation had two periods of oil and gas filling process: the first period was Sha2-Dongying The last period of sedimentation is filled with crude oil. The second period started from the end of deposition of Guantao Formation and has continued to this day. The period can be divided into two stages: the initial period of sedimentation of Guantao-Minghuazhen Formation is filled with crude oil In the middle of the sedimentation of the main and Minghuazhen formations, pyrolysis gas is the main part of the sedimentation; only the second phase of crude oil filling exists in the high-lying parts of the structure.